Robert Griffin III's injury status leaves more questions than answers surrounding the future of the Redskins' talented QB. (AP Photo)

The operation was a success, noted surgeon James Andrews said. Griffin "had a direct repair" of the lateral collateral ligament and "a re-do of his previous ACL reconstruction," Andrews said. A full recovery is expected.

Here's what we don’t know: Whether Griffin's name should be mentioned in the same sentence as Adrian Peterson, in regards to how fast he'll heal and how good he'll be when he does.

Until further notice, Peterson is the exception. He's an outlier. He's a freak of nature and science. Beginning an MVP-caliber season nine months after an ACL tear is way, way out of the ordinary.

Here's more of what we don’t know: Whether Griffin and Danny Manning should be in the same sentence.

No one will ever know how great Manning could have been. He's a college legend, he was the first pick in the 1988 NBA draft, and he was living up to the pick 26 games into his rookie season with the Los Angeles Clippers. Then he tore his right ACL, the first of three such injuries in a career that still stretched over 15 seasons.

Three, which means, of course, one knee got it twice. It was his right knee, and THE second came nine years later. By then, Manning was already established as a starter on the all-time NBA "What If?" team.

Different sport, yes. Different time frame, yes. Different era, without question — ACL reconstruction wasn't all that routine; Bernard King's famous tear having happened less than five years earlier. King missed more than two years. Now, Peterson missed one game and one offseason. He came back better. He was 26. Griffin is 22.

Probably the best-known recent NFL player with two tears of the same ACL is Kris Jenkins, the longtime nose tackle. The left one went in October 2009, and it went again in the season opener of 2010. He was 31 when that happened. He retired.

So where does RG3 fall within all of that?

Add that to the things we don't know. But roll through all those names, the players who tore their ACLs at young ages and older ages, who tore it once and tore it twice, who played basketball and football in college and the pros … and the only one that emerges as being just as good after as he was before is A.D.

That's right. Research it All Day, and all you come up with is All Day.

Logic tells us — demands us — to stop holding Peterson up as the target for Griffin to shoot for. History tells us that’s too high.

The optimistic estimates as the morning of Griffin's surgery wore on were that he could get back in six to eight months, and that he'll be ready for the Redskins' 2013 opener. It's not impossible, obviously. No two injuries or circumstances are the same, and no two athletes are, either.

But believing he'll be the same RG3 he was before is asking a lot.

And that's a damn shame.

He still could be great. He still could electrify, still could uplift a franchise, still could light up a whole league, still could have multiple playoffs, a few Super Bowls and endless indelible moments ahead. But, as with Danny Manning, we'll never know how much of all of those he could have produced.

Peterson isn't the norm. For one thing, he hasn't torn that ligament twice. That again is not unique, but it's pretty rare. In October 2010, Brian Cole, the team doctor for the Chicago Bulls, told the Times of Northwest Indiana that the likelihood of that happening is between 2.5 and 5 percent. "The most common reason is another random event," he told the paper.

Today, Cole has an even more intimate knowledge of ACLs than he did then: If you recognize his name, it's because he gives regular updates on Derrick Rose. When Rose blew his knee out in May, during last year's playoffs, he felt motivated enough to aim for this season's opener. Here, in early January, he has yet to do a full, no-restrictions practice.

Optimistic and realistic — sometimes they're just unfamiliar with each other.

By the way, when Cole did speak about multiple ACL tears, it was in connection with then-Purdue basketball star Robbie Hummel, who had torn his right ACL for the second time in eight months. Before the first injury, he was on his way to an All-America season, and his team was a Final Four contender. When he finally played a full season, last season, he was excellent.

Hummel was a late second-round NBA draft pick. He signed to play in Spain (and had to wait to play while recovering from ... an injury to the same knee, albeit a minor cartilage tear).

With only one tear, instead of two, he might be in the NBA instead. We'll never know.

With RG3, we know a little. We don't know a lot. And part of what we don’t know is if he'll ever be the RG3 we’ve grown to admire.